// collectiontopics/ReadOnly.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Using the Collections.unmodifiable methods

import onjava.Countries;

import java.util.*;

public class ReadOnly {
    static Collection<String> data =
            new ArrayList<>(Countries.names(6));

    public static void main(String[] args) {
        Collection<String> c =
                Collections.unmodifiableCollection(
                        new ArrayList<>(data));
        System.out.println(c); // Reading is OK
        //- c.add("one"); // Can't change it

        List<String> a = Collections.unmodifiableList(
                new ArrayList<>(data));
        ListIterator<String> lit = a.listIterator();
        System.out.println(lit.next()); // Reading is OK
        //- lit.add("one"); // Can't change it

        Set<String> s = Collections.unmodifiableSet(
                new HashSet<>(data));
        System.out.println(s); // Reading is OK
        //- s.add("one"); // Can't change it

        // For a SortedSet:
        Set<String> ss =
                Collections.unmodifiableSortedSet(
                        new TreeSet<>(data));

        Map<String, String> m =
                Collections.unmodifiableMap(
                        new HashMap<>(Countries.capitals(6)));
        System.out.println(m); // Reading is OK
        //- m.put("Ralph", "Howdy!");

        // For a SortedMap:
        Map<String, String> sm =
                Collections.unmodifiableSortedMap(
                        new TreeMap<>(Countries.capitals(6)));
    }
}
/* Output:
[ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO,
BURUNDI]
ALGERIA
[BENIN, BOTSWANA, ANGOLA, BURKINA FASO, ALGERIA,
BURUNDI]
{BENIN=Porto-Novo, BOTSWANA=Gaberone, ANGOLA=Luanda,
BURKINA FASO=Ouagadougou, ALGERIA=Algiers,
BURUNDI=Bujumbura}
*/
